The present invention relates generally to cement compositions useful in subterranean operations, and more specifically, to additives and cementitious components comprising oil suspensions of water soluble polymers, and methods of use in subterranean cementing operations.
Hydraulic cement compositions are commonly utilized in subterranean well completion and remedial operations. For example, hydraulic cement compositions may be used in primary cementing operations whereby strings of pipe such as casings and liners are cemented in well bores. In performing primary cementing, a hydraulic cement composition may be pumped into the annular space between the walls of a well bore and the exterior surfaces of a pipe string disposed therein. The cement composition is permitted to set in the annular space thereby forming an annular sheath of hardened substantially impermeable cement therein which supports and positions the pipe string in the well bore and bonds the exterior surfaces of the pipe string to the walls of the well bore. Hydraulic cement compositions may also be utilized in remedial cementing operations such as plugging highly permeable zones or fractures in well bores, plugging cracks or holes in pipe strings and the like.
Additives are used in cement compositions, among other purposes, to reduce fluid loss from the cement compositions to permeable formations or zones into or through which the cement compositions are pumped. In certain circumstances, it may be desirable to place a polymer within the cement composition, for example, to reduce loss of fluid from the cement composition and/or improve solids suspension therein.
The creation of cement compositions containing additives has typically involved combining a dry blend of such additives into the cement compositions with the aid of a blending facility to reach sufficient levels of additive concentration within the mixture. In some cases, such as off-shore cementing operations, the cement operation may not have sufficient blending facilities at hand to dry-blend the additive into a sufficiently-homogenous cement composition. These concerns usually necessitate the use of a liquid additive where a neat cement and/or certain additives are combined in an aqueous solution. With high molecular weight polymers, the active solution may be restricted to lower concentrations, as higher concentrations of the polymer may cause the solution to have an undesirably high viscosity prior to mixing with the remainder of the cement composition, making the solution with the polymer more difficult to mix into the cement composition. Moreover, lower concentrations of the polymer may not be as effective in reducing fluid loss of the cement composition, and providing other benefits in the operation. This may result in the undesirable and inefficient use of liquid additives, as excess amounts of solutions comprising the water-soluble polymer may be required to obtain the desired formulation.